1. Field of the Invention
The present invention relates to a lens assembly which includes a lens drive mechanism and an exposure control member.
2. Description of the Related Art
In a known lens shutter type camera, a drive mechanism which drives a photographing lens group (e.g., a focusing lens group) in an optical axis direction and an exposure control member, such as a shutter or a diaphragm, are integrally constructed as a lens assembly (lens-shutter unit/photographing-function unit) which is incorporated in a lens barrel. The lens assembly which includes the lens drive mechanism and the exposure control member is complex in structure. The individual mechanisms mounted in the lens assembly have various functions including an exposure controlling function or a focusing function, which have significant influence on picture quality. Accordingly, each mechanism must be highly precisely operated. However, due to the complex structure of the lens assembly, it is impossible to individually remove the mechanisms from the lens assembly to inspect the operation or performance thereof. For instance, in order to examine the operation of a shutter or a diaphragm at the manufacturing stage, it is necessary to assemble the lens assembly including the lens drive mechanism, which is inconvenient. Likewise, it is impossible to examine the operation of the lens drive mechanism until the lens assembly is completely assembled.
During the manufacturing process or during repair of the lens drive mechanisms, if only one of the lens drive mechanism and the exposure control mechanism is defective, it is necessary to replace the entire the lens assembly including other mechanisms, even though the other mechanisms operate properly, which is very uneconomical.
Moreover, the lens assembly is often provided with a detector such as a photo-interrupter to detect the operation state of the photographing lens group or the exposure control member. In general, the detector is secured by an adhesive or the like. However, it takes long time to dry and set the adhesive, and a possible leakage of the adhesive attenuates the performance of functional members or movable members within the lens assembly, including the detector itself. Furthermore, once the detector is adhered, it is difficult to detach the detector afterwards.
The present invention provides a lens assembly which can be easily assembled and disassembled and the function of the internal elements can be easily checked without wasting the elements.
The present invention provides a lens assembly in which a detector to detect the operation of the photographing lens group or the exposure control member, etc., can be easily attached to and detached from the lens assembly without damaging the detector.
For example, in an embodiment, a lens assembly is provided, including an exposure control unit having an exposure control member; a lens drive unit including a lens drive mechanism which moves a photographing lens group in an optical axis direction; center apertures which are formed in the exposure control unit and the lens drive unit, respectively, at the center portions thereof, which define a lens movement opening when the exposure control unit and the lens drive unit are connected to each other; and a lens support frame which supports the photographing lens group, the lens support frame being provided in the lens movement openings so as to move in the optical axis direction and driven via the lens drive mechanism.
The lens drive mechanism can include a lens drive motor; and a lens drive gear train provided between the lens drive motor and the lens support frame; wherein the lens drive motor and the lens drive gear train are supported by the lens drive unit.
The lens drive mechanism can further include a lens drive ring which is rotatably provided between the lens drive unit and the exposure control unit; wherein the lens drive ring is rotated via the lens drive motor and the lens drive gear train, so that the lens support frame is moved in the optical axis direction in accordance with the rotation of the lens drive ring.
The photographing lens group can include a front sub-lens group and a rear sub-lens group which optically function at a mutually close position and a mutually distant position in the optical axis direction; wherein the lens support frame includes a front lens frame and a rear lens frame which support the front and rear sub-lens groups, respectively. The rear lens frame is rotatable within a predetermined angular range in the lens drive unit, and is supported so as to linearly move in the optical axis direction at each rotational extremity of the predetermined angular range while restricting the rotation thereof. The rear lens frame viand the lens drive ring include first contact portions, and the first contact portions causing the rear lens frame to rotate and linearly move at the each rotational extremity, in accordance with the rotation of the lens drive ring. The front lens frame and the rear lens frame include second contact portions, the second contact portions moving the front lens frame and the rear lens frame between the mutually close position and the mutually distant position in accordance with the rotation of the rear lens frame, and the second contact portions linearly moving the front lens frame together with the rear lens frame, in accordance with the linear movement of the rear lens frame.
It is desirable for the exposure control member provided in the exposure control unit to include at least one of shutter sectors which open and close the center aperture of the exposure control unit and diaphragm sectors which vary a diameter of the center aperture of the exposure control unit, independently of the shutter sectors.
It is desirable for the exposure control member to be rotatable about rotation axes parallel with the optical axis of the photographing lens group so that the exposure control member is movable into the center aperture of the exposure control unit in accordance with the rotation thereof. The exposure control unit is provided with an exposure control member drive ring which is rotatable in the forward and reverse directions about the optical axis, so that the exposure control member is driven by the rotation of the exposure control member drive ring.
The exposure control member drive ring can be provided with a gear having a center located substantially on the optical axis; the lens drive unit including an exposure control motor and an exposure control gear train provided between the exposure control motor and the gear of the exposure control member drive ring. When the lens drive unit and the exposure control unit are connected to each other, the exposure control gear train and the gear of the exposure control member drive ring are engaged with each other.
The exposure control member drive ring can be provided on the outer peripheral surface thereof with a driven projection which extends in an externally radial direction of the exposure control unit; and a ring-rotating mechanism can be externally provided on the exposure control unit, the ring-rotating mechanism being provided with an engagement portion with which the driven projection engages and which rotates the exposure control member drive ring via the engagement portion and the driven projection.
The lens assembly can be mounted to a zoom lens barrel, and the ring-rotating mechanism can rotate the exposure control member drive ring in accordance with a zooming operation of the zoom lens barrel.
The exposure control unit can include shutter sectors which open and close the center aperture of the exposure control unit; a shutter drive ring which rotates about the optical axis in the forward and reverse directions to open and close the shutter sectors; diaphragm sectors which vary the diameter of the center aperture of the exposure control unit, independently of the shutter sectors; and a diaphragm drive ring which rotates about the optical axis in the forward and reverse directions to open and close the diaphragm sectors.
The shutter drive ring, which is supported in the exposure control unit, can be provided with a gear having a center located substantially on the optical axis; and the lens drive unit can include a shutter drive motor, and a shutter drive gear train provided between the shutter drive motor and the gear of the shutter drive ring, so that the shutter drive gear train and the gear of the shutter drive ring engage with each other when the lens drive unit and the exposure control unit are connected to each other.
The diaphragm drive ring can be provided on the outer peripheral surface thereof with a driven projection which extends in an externally radial direction of the exposure control unit. A ring-rotating mechanism can be externally provided on the exposure control unit, the ring-rotating mechanism being provided with an engagement portion with which the driven projection engages and which rotates the diaphragm drive ring through the engagement portion and the driven projection.
The lens assembly can further include at least one detection member, the detection member including at least one of a lens movement detector which detects the amount and direction of the movement of the photographing lens group in the optical axis direction, and an exposure control detector which detects the operation state of the exposure control member. The lens drive unit can be provided on the outer surface thereof with a support portion on which the detection member is supported.
The lens assembly can further include a cover member which is provided with engagement portions for engaging with the lens drive unit and the exposure control unit, the cover member being mounted to the outer surfaces of the lens drive unit and the exposure control unit via the engagement portions when the lens drive unit and the exposure control unit are interconnected, to thereby cover the support portion which supports the detection member.
The cover member can be provided with an elastically deformable abutment portion which abuts against the detection member to bias the detection member into the support portion of the lens drive unit.
The cover member can support a portion of an FPC, which is connected to the detection member, between the cover member and the outer surface of the lens drive unit.
In another embodiment, a lens assembly is provided, including a support barrel having a center opening; a lens support frame which supports a photographing lens group; a lens drive mechanism which moves the lens support frame within the center opening of the support barrel in the optical axis direction; and an exposure control member which is movable into the center opening. The support barrel includes a lens drive unit having at least part of the lens drive mechanism, and an exposure control unit which supports the exposure control member. The lens drive unit and the exposure control unit are interconnected upon each of the lens drive unit and the exposure control unit being independently assembled.
In another embodiment, a lens assembly is provided, including an exposure control unit having an exposure control member; a lens drive unit including at least a part of a lens drive mechanism which moves a photographing lens group in an optical axis direction; center apertures which are formed in the exposure control unit and the lens drive unit, respectively, at the center portions thereof, which define a lens movement opening when the exposure control unit and the lens drive unit are connected to each other; a lens support frame which supports the photographing lens group, the lens support frame being provided in the lens movement openings so as to move in the optical axis direction and so as to be driven via the lens drive mechanism provided in the lens drive unit; a lens movement detector which detects the amount and direction of the movement of the lens support frame; an exposure control detector which detects the operational state of the exposure control member; support portions provided on the outer surface of the lens drive unit to support the lens movement detector and the exposure control detector; and a cover member which is provided with engagement portions for engaging with the lens drive unit and the exposure control unit, the cover member being mounted to the outer surfaces of the lens drive unit and the exposure control unit via the engagement portions when the lens drive unit and the exposure control unit are interconnected, to thereby cover the support portions which support the detectors.
The cover member can be provided with a pair of elastically deformable abutment portions which abut against the lens movement detector and the exposure control detector to bias the lens movement detector and the exposure control detector into the support portions of the lens drive unit.
The lens assembly can further include an FPC which is connected to the lens movement detector and the exposure control detector; wherein the cover member holds a part of the FPC between the cover member and the outer surface of the lens drive unit.
In another embodiment, a lens assembly is provided, including an exposure control mechanism; a lens drive mechanism which drives a photographing lens group in an optical axis direction; and a detector which detects the operational state of at least one of the lens drive mechanism and the exposure control mechanism. The lens assembly includes front and rear function units which can be divided, one of the front and rear function units being provided on the outer peripheral surface thereof with a detector receiving portion which receives therein the detector. A cover member having engagement portions for engaging with the front and rear function units can be mounted to the outer surfaces of the front and rear function units via the engagement portions when the function units are interconnected, to thereby cover the detector receiving portion.
The cover member can be provided with an elastically deformable abutment portion which abuts against the detector to bias the detector into the detector receiving portion of the function unit.
The lens assembly can further include an FPC which is connected to the detector; wherein the cover member holds a part of the FPC between the cover member and the outer surface of the function unit.
The present disclosure relates to subject matter contained in Japanese Patent Application No.2001-82923 (filed on Mar. 22, 2001) which is expressly incorporated herein by reference in its entirety.